Circuit breakers typically have an operating mechanism, and a tripping mechanism, such as, a thermal trip assembly and/or a magnetic trip assembly, which are automatically releasable to effect the tripping operation, and then are manually resettable following the tripping operation.
Such circuit breakers, have commonly been referred to as “miniature” circuit breakers, and have been in use for many years. Their design has been improved upon so as to provide an effective, reliable circuit breaker, which can be easily and economically manufactured on a large scale. In addition, circuit breakers of this type may be utilized in conjunction with are fault and/or ground fault trip mechanisms as well.
Circuit breakers of this type include at least one set of separable contacts disposed within a non-conductive housing. Typically, there is a fixed contact attached to the housing and a movable contact coupled to the operating mechanism. The operating mechanism includes a movable operating handle that extends outside of the housing. The operating mechanism further includes an operating arm, upon which the movable contact is disposed, the trip mechanism, and a cradle. The cradle is coupled to a spring and is pivotally disposed between the trip mechanism and the operating arm. One portion of the cradle pivots with respect to the housing while another portion of the cradle has a latch ledge, which is latched by the trip mechanism.
The operating member or handle has essentially two or three stable positions: (1) ON and OFF; or (2) ON, OFF and TRIPPED. In the latter case, the three positions tell the operator what condition the circuit breaker is operating in when viewed. In normal operation, the handle is maintained in the ON position. Then, once the trip mechanism is automatically released, in order to protect electrical circuitry from damage due to an overcurrent condition, such as, an overload or relatively high level short circuit, the handle automatically moves to the TRIPPED position. The circuit breaker must then be reset, as is well known in the art, by moving the handle beyond the OFF position to a RESET position from which the handle returns to the OFF position when released. The circuit breaker may then be manually operated from the OFF to the ON position, in order to allow the circuit breaker to resume normal operation. In addition, the handle is manually maneuverable from the ON to the OFF position if it is desired to open the protected circuit. A typical circuit breaker is calibrated, for example, to maintain a current flow of 100% of its rated current and to trip within predetermined times at 135% or 200% of such rated current.
The following patents are indicative of the state of the art for miniature circuit breakers: U.S. Pat. No. 6,005,207 (Bernard DiMarco, et al.), U.S. Pat. No. 6,172,586 (James F. Ferree, et al.), U.S. Pat. No. 6,392,512 (James Edward Ferree, et al.), U.S. Pat. No. 6,850,134 (Edward E. Lias, et al.), U.S. Pat. No. 6,894,594 (Joseph P. Fello, et al,), and U.S. Pat. No. 7,800,007 (Narayansamy Soundararajan, et al.).
However, there is room for improvement in circuit breaker operating mechanisms to prevent arcing, magnetic flux physically displacing component, heat degenerating components.
This invention improves on the deficiencies of the prior art, and provides an inventive molded circuit breaker (MCB).